Keep your eyes on it, first and foremost. Know that they attack bottom-up. They tend to come straight up at you. To be realistic, throwing a punch in the water is like slow motion. Anybody that can pull it off and actually cause damage, give me a call. But, the gills and the eyes are probably your highest chance of creating pain. Once again, just like with anything, you want to create pain, you want to induce pain, and hopefully it leaves you alone. That is the number one goal, and create distance if you can, but as a last resort, you go for the gills, you go for the eyes. You literally want to shove your thumbs into the shark's eyes. If you grab the gills, you want to stick your fingers in the vents and you want to try and rip them out.